The invention relates to a material for storing hydrogen which contains titanium and iron in a mutual ratio in gram-atoms between 4:1 and 0.67:1. The invention further relates to the hydrides formed from such materials, to a method for storing and giving off hydrogen while using such materials and their hydrides, and to an apparatus containing such materials and their hydrides for storing and giving off hydrogen.
It is known that mixtures of iron and titanium in the form of compounds and alloys are suitable for storing hydrogen by forming hydrides under pressure at ambient temperature. By decreasing the pressure surrounding the material and/or heating the material, hydrogen is released from the material. U.S. Pat. No. 3,516,263 and U.S. Pat. No. 3,508,414 disclose a material which contains, by weight 35-75% Ti, the remaining percent being Fe. It appears that in practice an elaborate treatment of the material is necessary, after preparation, before the material can be made to quickly absorb and release hydrogen at ambient temperature.
This "activation treatment" may, for example, consist of heating the material to a temperature of 400.degree. C. or higher in a vacuum and while continuously evacuating, followed by cooling the material to room temperature and supplying hydrogen to a pressure of approximately 35 atmospheres, whereafter the hydrogen is again released from the material by vacuum-pumping and heating. This procedure must be repeated various times to obtain such a degree of activation that at approximately 20.degree. C. the material can reversibly absorb and release hydrogen at a sufficient speed which depends upon the pressure surrounding the material.